Over the course of the six episodes (and two reworks contained in the summer bonus missions) the game offers a mix of different types of stealth. Levels like Paris and Bangkok let you move through crowds, changing costumes like a chameleon to stay one step ahead of suspicion as you trigger events and manipulate people into doing your bidding. On the flip-side, Marrakesh and Colorado require you to do your best Sam Fisher impression to avoid a full-scale firefight, with you stalking dark corridors and brutally taking out sentries to avoid the alarm being raised.
Each of the levels has a different texture with different underpinning mechanics and a slightly different rule set when it comes to what you can and can't get away with. In Hokkaido, for example, this final level of what IO Interactive has now termed Season 1, the security is all handled by an AI and you are initially hampered by electronic locks controlled by RFID chips in your clothing. This can make getting access tricky, but if you manage to get an RFID chip with all-access, you'll find that physical security — and here I'm talking about burly folk with big guns stopping you walking around where you shouldn't be — is thin on the ground, allowing you to mill around largely unmolested.
On the other hand, mechanical security in the sleepy Italian town of Sapienza is lax and as such access to the mansion your target inhabits is as easy as vaulting a low wall or sliding into an open window, but the physical security — again, burly guys with big guns — is top notch, with most rooms full of patrols and sentries telling you where you can and can't be.
Over the course of the game you'll learn what type of stealth suits you best: whether you want to sneak in and make your kills look like accidents; go full John Wick and assassinate your target and everyone they're standing near in a hail of gunfire; or even my preferred approach, the near silent tornado that roams the hallways and rooftops of levels, massacring everyone and hiding them in a convenient chest-freezer or laundry basket within arm's reach.
As you complete the levels repeatedly you'll earn experience for each individual level, with each challenge giving you experience towards the mastery rank for that mission. Different levels of mastery give you access to different entry points for the mission (including several opportunities to start undercover), a series of dead drops to let you smuggle items into the mission for you to collect in the field, or even a selection of different weapons and items that you can put into your armoury and save for a rainy day or one of the many other operations you'll end up undertaking.
Your armoury gets quite beefy over the course of the campaign too. If you've unlocked everything you'll reach the end with a selection of different custom-made guns, a host of poisons and more explosives than any assassin could ever conceivably need. Highlights include a tiny silenced pistol that will go unnoticed during a groping from security; an exploding cell phone that draws your enemies to it, exploding when they answer; or even a syringe that makes you opponents run to the nearest toilet or bin for a repeat of the day's breakfast. These items can all be used by savvy players to get past a variety of problems or to try and meet several of the game's challenges.
The challenge system is a lot of fun but also highlights one of the biggest problems with the game: If you're playing it well, acing each and every mission, you're actually not going to unlock a whole lot of stuff. There's a slight dissonance in that if you're looking to achieve challenges you can't just sneak into the penthouse of rockstar Jordan Cross and shoot him in the back of the head; no, you'll have to subject him to his own perverse version of Groundhog Day, continually bringing him back to life in repeated restarts so you can drop a coconut on his head, or push him off a hotel roof or perhaps just smother him to death in his own birthday cake in front of his adoring friends and family.